Brush part for electric toothbrush

ABSTRACT

A brush part for an electric toothbrush in which tufts of bristles are arranged in polygons, and in which the tufts of bristles lean, either around the polygons or inwardly and outwardly, so that the tuft alignments converge and preferably cross.

This invention relates to bristles for electric toothbrushes, inparticular to bristle clusters for electric toothbrushes.

Electric toothbrushes generally comprise a handle which contains interalia a power supply and a drive motor, a neck extending from the handleand containing a transmission means e.g. a drive shaft, and a brush partwhich includes a bristle holder mounted thereon for rotary motion abouta rotation axis, and connected by the transmission means to the motor. Acluster of tufts of bristles is mounted on a surface of the holder,extending generally in a bristle direction, with their end closest tothe bristle holder, i.e. their base end, set in the holder and theirdistal end furthest from the holder. Generally the bristle tufts extendgenerally parallel to the rotation axis. Generally the handle, neck andbristle holder lie along a longitudinal axis direction, and the rotationaxis is at a transverse angle to this axis direction, e.g. generally atright angles. Commonly the bristle holder is replaceable on the handle,often together with the neck. Often the rotary motion is oscillatory,i.e. motion involving reciprocal angular displacement about a meanposition, and the term “rotary” herein includes oscillatory rotarymotion. Sometimes the rotary motion also involves a reciprocal back andforth movement of the bristle holder along the rotational axisdirection.

Numerous constructions of electric toothbrush of this type are known,for example the applicant's own Dr BEST “E-FLEX” (™) electric toothbrushlaunched in 2000 which has a brush part mounted for oscillatory rotarymotion.

Electric toothbrushes are known from U.S. Pat. No. 4,608,968 and DE-G-8807 968.6 in which the tufts of bristles are arranged leaning outwardlyrelative to the rotation axis, with progressively less steeply leaningtufts toward the centre of the cluster, and with tufts at the centre ofthe bristle cluster arranged parallel to the rotation axis. EP-A-0 765642 discloses electric toothbrush tuft clusters which have their bristletufts inclined an a non-zero angle to the rotation axis, leaning towarda central longitudinal plane of the toothbrush. WO-A-0041592 disclosesan oscillatory rotary electric toothbrush bristle cluster in which thetufts of bristles are inwardly leaning toward the rotation axis in aconical or pyramidal arrangement.

For “manual” toothbrushes, i.e. toothbrushes without an electric motorand which operate solely by the motion of the user's hand, bristleconfigurations are known in which as viewed from certain directions,particularly from the side, the bristle tufts, or their extrapolation,are seen to converge and cross. This is for example disclosed inDE-A-633 556, DE-G-82 02 897.6, FR-A-683 311, FR-A-2,624,360, U.S. Pat.No. 2,242,743, U.S. Pat. No. 3,085,273, U.S. Pat. No. 4,010,509, U.S.Pat. No. 4,081,876, U.S. Pat. No. 4,776,054, U.S. Pat. No. 5,274,873 andWO-A-99/23910. DE-A-44 12 301 and DE-A-35 44 256 disclose electrictoothbrushes with bristles which are crossed in an “X” arrangement.

These known bristle clusters do not optimise tooth cleaning,particularly the cleaning of the interproximal spaces between the teethwhere dirt can collect. It is an object of the present invention toprovide an improved bristle cluster for electric toothbrushes of theabove-described type.

According to a first aspect of this invention a brush part for anelectric toothbrush is provided which includes a bristle holder mountedfor rotary motion about a rotation axis,

a plurality of first tufts projecting from a surface of the bristleholder and having their bases arranged in a polygon around the rotationaxis and leaning outwardly away from the rotation axis so that theirdistal end is further out from the rotation axis than their base, and aplurality of second tufts projecting from a surface of the bristleholder and having their bases arranged in a polygon around the rotationaxis, characterised by:

the first and second tufts having their bases at different radialdistances from the rotation axis, the first and second tufts orientedrelative to the rotation axis such that at a point along theirbase-distal end length the first and second tufts are respectively atradial distances from the rotation axis with a difference in theirrespective radial distances less than the difference in the respectiveradial distances of their bases from the rotation axis.

According to a second aspect of this invention a brush part for anelectric toothbrush is provided which includes a bristle holder mountedfor rotary motion about a rotation axis,

a plurality of first tufts projecting from a surface of the bristleholder and having their bases arranged in a polygon around the rotationaxis, and a plurality of second tufts projecting from a surface of thebristle holder and having their bases arranged in a polygon around therotation axis, characterised by:

the first tufts comprising an inner polygon in which at least one tuftis mounted inclined at an angle such that the distal end of the tuft isfurther around the polygon than the base end in a first direction, and

the second tufts comprising an outer polygon in which at least one tuftis mounted inclined at an angle such that the distal end of the tuft isfurther around the polygon than the base end, in a second directionopposite to the first direction.

In both the first and second aspects of this invention the bristleholder is connectable to a toothbrush handle containing an electricdrive motor and capable of being driven in rotary motion by the drivemotor when connected thereto about a rotation axis generally transverseto an axis between the brush part and the handle. Such rotary motion maybe oscilatory rotary motion.

Preferably in the toothbrush head of the first aspect of this inventionthe bases of the second tufts are located at a greater radial distancefrom the rotation axis than are the bases of the first tufts.

Preferably in this brush part of the first aspect of the invention at apoint along their base-distal end length the first and second tufts arerespectively at the same radial distances from the rotation axis, i.e.so that the difference in their respective radial distances at thispoint is zero. Preferably further distally along the base-distal lengthfrom this point the difference in their respective radial distances ofthe first and second tufts increases.

Preferably in this brush part of the first aspect of the invention thefirst and second tufts are circumferentially adjacent to each other atthe point of minimum difference, e.g. of zero difference, in theirrespective radial distances, on a circle centred on the rotation axis.

One embodiment of this brush part of the first aspect of the inventioncomprises a plurality of second tufts having their bases furtherradially out from the rotation axis than the bases of the first tufts,and aligned parallel to the rotation axis.

A second embodiment of this brush part of the first aspect of theinvention comprises a plurality of second tufts having their basesfurther radially out from the rotation axis than the bases of the firsttufts, and leaning inwardly toward the rotation axis so that theirdistal ends are at less distance radially from the rotation axis thantheir base.

A third embodiment of this brush part of the first aspect of theinvention comprises a plurality of second tufts having their basesfurther radially out from the rotation axis than the bases of the firsttufts, and leaning outwardly away from the rotation axis so that theirdistal end is further out from the rotation axis than their base, but ata lesser angle of lean relative to the rotation axis than the firsttufts.

Preferably in this brush part of the first aspect of the invention thedistal ends of the first tufts are further radially out than the distalends of the first tufts, although the distal ends of the first tufts maybe at the same or lesser radial distance than the distal ends of thesecond tufts from the rotation axis. This allows a preferred arrangementin which the respective lean of the outwardly leaning first tufts andthe orientation of the second tufts is such that as viewed along a linetangential to a circle centred on the rotation axis and mid way betweenthe bases of the first and second tufts circumferentially adjacent firstand second tufts as seen superimposed are seen to cross each other. Insuch an arrangement the tufts may cross at the mid point between thebase and the distal ends along the tufts, or closer to the base orcloser to the distal ends of the tufts.

Preferably in this brush part of the first aspect of the invention thesecond tufts also have their bases arranged in a polygon around therotation axis in which in such a polygon the bases of the second tuftslie outside and preferably concentric with the polygon of bases of thefirst tufts. Suitably there may be one or more such polygon of firsttufts and/or one or more such polygon of second tufts.

For example in this brush part of the first aspect of the inventionthere may be two or more polygons of first tufts, one within the otherpreferably concentrically about the rotation axis, the respective firsttufts in these polygons leaning outwardly at the same or different anglerelative to the rotation axis, and for example having their first tuftsarranged on radii from the rotation axis. In such an arrangement theremay for example also be two or more polygons of second tufts, one withinthe other. A preferred arrangement of first and second tufts comprises,proceeding radially outward from the rotation axis: a polygon of basesof first tufts; a polygon of bases of second tufts oriented parallel tothe rotation axis; another polygon of bases of first tufts; anotherpolygon of bases of second tufts oriented parallel to the rotation axis.

In this brush part of the first aspect of the invention a polygon ofsecond tufts may be the radially outermost tufts of the cluster ofbristle tufts.

Preferably in this brush part of the first aspect of the invention theangle relative to the rotation axis at which the outwardly leaning firsttufts may lean may be between 2.5 to 35°, preferably between 5 to 10°,for example typically around 8-10°.

If in this brush part of the first aspect of the invention the secondtufts are inwardly leaning as mentioned above, they may be combined inthe cluster with first tufts which lean outwardly at between 2.5 to 35°,preferably between 5 to 25°, for example between 10 to 15°, typicallyaround 12°, and the respective first and second tufts may leanrespectively outwardly and inwardly at the same or different anglesrelative to the rotation axis.

In the clusters described above in this brush part of the first aspectof the invention where a polygon of bases of outwardly leaning firsttufts is within a polygon of bases of second tufts, the tufts may bearranged so that first tufts are radially (relative to the rotationaxis) adjacent to a gap between two circumferentially adjacent secondtufts. Such an arrangement allows an outwardly leaning first tuft tolean outwardly between flanking pairs of second tufts which are orientedsubstantially parallel to the rotation axis, and a second tuft orientedsubstantially parallel to the rotation axis may be between flankingpairs of outwardly leaning first tufts. It alternatively allows anoutwardly leaning first tuft to lean outwardly between flanking pairs ofinwardly leaning second tufts, and an inwardly leaning second tuft tolean inwardly between flanking pairs of outwardly leaning first tufts.Alternatively it allows an outwardly leaning first tuft to leanoutwardly between flanking pairs of second tufts which also leanoutwardly, and a second tuft leaning outwardly to be between flankingpairs of outwardly leaning first tufts. With such arrangements of firstand second tufts it is appropriate that there are the same numbers oftufts in the respective inner first and outer second polygons.

Alternatively in this brush part of the first aspect of the inventionthe outwardly leaning first tufts may be arranged in groups of two ormore circumferentially adjacent first tufts, and/or the second tufts maybe arranged in groups of two or more circumferentially adjacent secondtufts. In such arrangements, such groups of first tufts may becircumferentially between pairs of second tufts, or vice versa.

Outwardly and inwardly leaning tufts in this brush part of the firstaspect of the invention may lean inwardly along radii centred at therotation axis, so that the tufts lean respectively straight away fromand toward the rotation axis, i.e. perpendicular to the direction ofrotation. In such an arrangement the respective directions of lean inprojection converge radially on the axis of rotation. Alternatively therespective directions of lean in projection may be along lines parallelto each other, preferably with a parallel line between the directions oflean passing through the axis of rotation.

Turning now to the brush part of the second aspect of the invention, atleast one tuft in each of the first and second polygons is inclinedaround the polygon as described, and preferably all of the tufts in thepolygons are inclined.

In this brush part of the second aspect of the invention, relative tothe axis of rotation the angle at which the at least one, or preferablyall the tufts, are inclined such that the end of the tuft which isfurthest from the surface of the bristle holder is further around thepolygon than the end of the tuft which is mounted in the surface maysuitably be in the range 1 to 30°, typically 3 to 15°, especially 7-12°.If the ends of the tuft which are mounted in the bristle holder lie in aplane, e.g. if the surface of the bristle holder is a flat surfacedefining such a plane, then this angle may be in the range 89 to 60°,typically 87 to 80°, especially 83-78° to this plane.

In this brush part of the second aspect of the invention the inclinedtuft(s) may be aligned in a direction substantially parallel to anadjacent side of the polygon. Alternatively the tuft(s) may be inclinedinwardly or outwardly, relative to the centre of the polygon, forexample in a direction in the range 0°-30°, preferably 0°-10°, inwardlyor preferably outwardly angled relative to the centre of the polygon asviewed in plan, relative to the direction of an adjacent side of thepolygon. The consequence of this latter inclination is that the end ofthe tuft which is furthest from the surface of the bristle holder isfurther out or in relative to the centre of the polygon, than is the endof the tuft which is mounted in the surface.

In the inner first and outer second polygons in this brush part of thesecond aspect of the invention, the respective inclined tufts ofbristles are inclined in respective opposite directions around thepolygon. For example the tuft(s) in the inner first polygon may beinclined such that the distal end of the tuft(s) is further around thepolygon than the base end of the tuft in an anti-clockwise direction,whilst the tuft(s) in the outer second polygon may be inclined such thatthe distal end is further around the polygon than the base end in aclockwise direction, or vice versa.

In such first and second polygons of this brush part of the secondaspect of the invention, the angles of inclination in the respectivedirections around the polygon may be the same or different, and/or thetuft(s) of the inner first and outer second polygons may differ inwhether they are aligned with an adjacent side of the polygon or whetherthey are inclined inwardly or outwardly. For example the tuft(s) of theinner polygon may be inclined at a smaller angle relative to the axis ofrotation in the direction around the polygon than the outer polygon, Forexample the tufts of the inner polygon may be inclined parallel to anadjacent side of the polygon, whilst the tufts of the outer polygon areinclined outwardly.

As described herein the position of a tuft relative to the axis ofrotation refers to the position of the centre of its base or distal end.In the brush part of both the first and second aspects of the inventionthe above described polygons are preferably regular polygons. In suchabove described inner and outer polygons of tufts there may be forexample be the same or different numbers of first and second tufts inthe respective inner and outer polygons. In both the first and secondaspects of the invention the distal ends of the first and second tuftsof the cluster may all be at the same distance from the surface of thebristle holder, e.g. so that the distal ends lie in a planeperpendicular to the rotation axis.

In both the first and second aspects of this invention the first andsecond tufts may be combined in the cluster with one or more other kindsof tufts, called generally herein “third tufts”. Such one or more thirdtuft may be provided in the cluster for example to create a suitabledensity of tufts for effective tooth cleaning. Such one or more thirdtuft may be located at any position in the cluster. For example thecluster may comprise one or more polygon of tufts which include both oneor more first tuft and one or more third tuft, and/or one or morepolygon of tufts which include both one or more second tuft and one ormore third tuft. Alternatively such third tufts may be provided in oneor more third polygon which includes third tufts, and for example maycontain only third tufts. Such third polygon may have a common centrewith the above-mentioned one or two polygons. For example such thirdpolygon may be situated within and surrounded by, or outside of andsurrounding, the above-mentioned first and second polygons. For examplesuch a third polygon may be within and surrounded by the innermost of apolygon of first or second tufts. For example such third polygon may beradially between the inner first and outer second polygon. There may forexample be a single third tuft at the centre of the first or secondpolygon.

For example in the brush head of both the first and second aspects ofthe invention such one or more third tuft may comprise one or more tuftaligned parallel with the rotation axis. For example in the first aspectof the invention such one or more third tuft may comprise one or moretuft leaning in the direction of rotation, e.g. as disclosed in EP-A-0765 642, or leaning inwardly toward the rotation axis e.g. as disclosedin WO-A-0041592, the contents of which are incorporated by reference.

For example in the brush part of the first aspect of this invention, twosuch above-described respective inner and outer polygons of respectivelyfirst and second tufts may comprise the two outermost tufts of thecluster, and there may be such third tufts within the inner polygon,e.g. forming an innermost third polygon. The third tufts may for exampleextend further from the surface than do the first and second tufts,which all may have their distal ends at the same perpendicular distancefrom surface. In this arrangement the third tufts form a central peak,and the distal ends of the third tufts may be cut obliquely to theirlength.

For example in the brush part of the second aspect of the invention thecluster of bristles may comprise three polygons of tufts, being a firstinner polygon and a second outermost polygon surrounding the first innerpolygon, with all of the tufts in these first and second polygons beinginclined at an angle such that the distal end of the tuft is furtheraround the polygon than the base end but in respectively oppositedirections around the polygon, together with a third innermost polygonof tufts within the first inner polygon, the tufts of this innermostthird polygon being parallel to the axis of rotation. These variouspolygons preferably have a common centre. In this embodiment there mayalso be a single third tuft at the centre of the polygons being alignedparallel to the axis of rotation.

In the brush heads of both aspects of this invention the number of tuftsin the various above-mentioned polygons may be determined in practice bythe dimensions of the tufts and the bristle holder. Typically bristletufts as used in electric toothbrushes have a cross sectional dimensionof ca. 1 mm, and the width of the bristle surface of a rotatable bristleholder of an electric toothbrush is ca. 10-12 mm. Typically theoutermost polygon of tufts contains 10-20 tufts. Typically a polygonimmediately radially inward of such an outermost polygon of tufts 8-12tufts. The above-mentioned polygons in both aspects of the presentinvention are preferably regular polygons.

The ends of the bristles remote from the surface of the bristle holdermay be profiled in various ways.

For example as mentioned above in the brush part of the first aspect ofthis invention, an innermost polygon of third tufts may for exampleextend further from the surface than do the first and second tufts,which all may have their distal ends at the same perpendicular distancefrom surface. In this arrangement the third tufts form a central peak,and the distal ends of the third tufts may be cut obliquely to theirlength.

For example in the brush part of the second aspect of this invention theends of all the tufts of the polygon(s) in which at least one tuft ismounted inclined at an angle such that the distal end of the tuft isfurther around the polygon than the base end, may be in a planeperpendicular to the axis of rotation.

Alternatively for example in the brush part of the second aspect of thisinvention the ends of the tufts may form a central peak. For examplesuch a cluster may comprise first and second inner and outer polygons oftufts including the inclined tuft(s), with an innermost polygon of thirdtufts aligned parallel to the rotation axis, with optionally a singlecentral tuft, and the ends of the bristles of the innermost polygon andof the central tuft (if present) may be profiled to form a central peak.The ends of the tufts of the innermost polygon may be cut obliquely totheir length so as to incline upwards toward the centre of the polygon.In such a central peak the ends of the tufts may be profiled into agenerally conical shape with its apex pointing away from the bristlesurface.

Alternatively in the brush part of the second aspect of this inventionthe ends of the tufts may form a concavity about the centre of thecluster, and for example the ends of the tufts may form a central peakabout the centre of this concavity so that the height of the polygonsdips between the outermost and innermost polygons. The ends of the tuftsof this peak may be profiled into a generally domed shape, e.g. agenerally hemispherical dome with its radius pointing away from thebristle surface. For example in such an arrangement the tufts of theinnermost polygon may be higher that the tufts of the outermost polygonby ca. 0.5-1.5 mm, and the tufts of the intermediate polygon may belower that the tufts of the outermost polygon by ca. 0.5-1.5 mm.

For example alternatively in another embodiment of the brush part of thesecond aspect of this invention the ends of all the tufts may beprofiled in a concave generally cylindrical surface having thelongitudinal axis of the cylinder aligned perpendicular to the axis ofrotation. A typical width for the cluster of the brush part is ca.10-12.5 mm measured perpendicular to the bristle direction. With such awidth a suitable radius of curvature of the cross section of such acylindrical surface is ca. 8-12 mm, e.g. 10-11 mm.

The term “conical” as used herein including shapes with other than truecircular cross sections across the axis of rotation e.g. pyramid shapes,and with curved sides e.g. ogival shapes. The term “sphere” and derivedterms as used herein including shapes with other than true circularcross sections e.g. oblate spheroids and ellipsoidal shapes. The term“cylindrical” as used herein includes true cylinders i.e. a shape havingstraight longitudinal sides and a circular cross section, with thelongitudinal axis of the cylinder passing through the centre of thecircular section. The term also includes distorted cylinders, e.g.shapes with convex bulging longitudinal sides e.g. “barrel” shapes, andshapes with concave sides, i.e. wider at the cylinder ends than at awaist partway between the ends, provided however that the radius ofcurvature of the convex or concave sides is greater than the radius ofcurvature of the cross section shape. Also the term “cylinder” includessuch shapes with oval or oblate circular, or polygonal, includingpolygonal with rounded corners or sides, cross section.

The brush part of this invention appears to be suitable for all electrictoothbrushes in which the bristle holder is mounted for and moveable inrotary motion about an axis transverse to, preferably substantiallyperpendicular to, the longitudinal head—handle axis of the toothbrush,substantially parallel to the bristle direction, and passing through orclose to the centre of the bristle pattern. Preferably the rotary motionis oscillatory, i.e. involving rotation through an angle in one rotarydirection, alternating with rotation through substantially the sameangle in the opposite rotational direction.

Preferably this rotary motion is combined with reciprocal motion of thebristles along the bristle direction, i.e. up and down the bristledirection. For example the motion of the bristle holder, combining suchoscillatory rotary and reciprocal motion, may be reciprocally helical.Suitable drive mechanisms to drive the bristle holder in this way areknown, for example in U.S. Pat. No. 5,577,285, WO-A-01/06946 andWO-A-01/06947, the contents of which are included herein by reference.The drive speeds, amplitudes, and oscillation frequencies, e.g. ca.3000-6000 rpm achievable by means of such known drive mechanisms arebelieved to be suitable for the brush part of both aspects of thepresent invention.

Therefore the invention further provides an electric toothbrush having abrush part as described above. For example the brush part of thisinvention may be connectable, preferably replaceably connectable, to atoothbrush handle containing an electric drive motor which when soconnected can drive the brush part in the above-described rotary motion.For this purpose the brush part suitably comprises part of a toothbrushhead which is itself provided with connection means by which the brushpart may be connected to the handle and to the motor. The brush part mayfor example be rotatably mounted on the toothbrush head, for example byknown means, such as an axle mounting, many types of which are known.The connection means may comprise a hollow neck part extendinglongitudinally between the head and the handle and enclosing a driveshaft by which the motor can drive the brush part via suitabletransmission means. The neck part may itself be connectable, preferablyreplaceably, at its end remote from the head, to the handle in a mannerwhich also connects the drive shaft to the motor. Alternatively the headmay itself be connectable, preferably replaceably, to the neck part atits end remote from the handle, to the neck part in a manner which alsoconnects the drive shaft to the brush part. Many means by which themotor can drive the shaft, and the shaft can drive the brush part, toachieve such motion are known.

Generally an electric toothbrush is an elongate structure whichcomprises a head (including the brush part) and handle disposed along ahead—handle axis being the length of the toothbrush, and for example ifthe bristle holder performs oscillatory rotary motion the longitudinalaxis of the part cylindrical surface may oscillate about a meanalignment perpendicular to the length of the electric toothbrush.

The toothbrush bristle holder and the bristles themselves of the brushpart of this invention may be made of materials which are conventionalin the field of electric toothbrush manufacture, e.g. respectively ofplastics materials and bristles of nylon, e.g. Tynex™ material fibres.The plastics material parts of the bristle holder and other plasticsmaterial parts of the toothbrush may be made by an injection mouldingprocess, and accordingly the invention further provides a process formaking a toothbrush as described herein, comprising injection mouldingof plastics material. Further the invention provides an injection mouldsuitable for use in such a process.

The bristle cluster of this invention is believed to provide improvedtooth cleaning relative to know bristle clusters.

The invention will now be described by way of example only withreference to the following figures which show:

FIG. 1 shows the overall schematic layout of an electric toothbrushhaving a brush part as described.

FIGS. 2 and 3 show a side and a plan view of a tuft cluster of the firstaspect of this invention.

FIGS. 4 and 5 show a side and a plan view of another tuft cluster of thefirst aspect of this invention.

FIGS. 6 and 7 show a side and a plan view of another tuft cluster of thefirst aspect of this invention.

FIGS. 8 and 9 show a side and a plan view of another tuft cluster of thefirst aspect of this invention.

FIGS. 10, 11, 12 and 13 show part views of the clusters of FIGS. 2 to 9,and of another cluster of the first aspect of this invention.

FIG. 14 shows a part view of a cluster of the first aspect of thisinvention.

FIG. 15 Shows perspective and plan views of a bristle cluster of thesecond aspect of this invention.

FIG. 16 Shows a side, perspective and plan view of another bristlecluster of the second aspect of this invention.

FIG. 17 Shows a side and perspective view of another bristle cluster ofthe second aspect of this invention.

FIG. 18 Shows side and perspective views of another bristle cluster ofthe second aspect of this invention.

FIG. 19 Shows a plan view of and a section through another bristlecluster of the second aspect of this invention.

FIG. 20 Shows a plan at the bristle surface, a plan view and a side viewof another bristle cluster of the second aspect of this invention.

Referring to FIG. 1 an electric toothbrush is shown overall in side view10. The toothbrush 10 comprises a handle 11 by which it may be held, andwhich includes a drive motor, batteries, controls etc. (not shown). Thehandle 11 is replaceably connected at link 12, suitably a bayonetconnection, to a replaceable section 13 including a head 14 at the endof the section 13 remote from handle 11 and a neck part 15. The assemblyof handle 11, replaceable section 13 and head 14 are disposed along thelength direction A—A of the toothbrush 10. In the head 14 is mounted abrush part comprising a bristle holder 16, from which a cluster ofbristles 17 extend in a general bristle direction B—B generallyperpendicular to length A—A. The holder 16 is driven by the motor (notshown) via drive shaft 18 (shown generally) extending along inside theneck part 15. The bristle holder 16 is mounted on an axle (shown 18 inFIG. 3) in head 14 for oscillatory rotation about an axis passingthrough the centre of the bristle cluster 17 and parallel to the bristledirection B—B and for simultaneous reciprocal movement up and down thisaxis as shown by the arrows.

In use the holder 16 performs simultaneously an oscillatory, i.e.reversing, rotary motion about an axis of rotation parallel to bristledirection B—B and passing through the centre in plan of the cluster ofbristles 17, and a reciprocal motion up and down along the bristledirection B—B. The amplitude of the oscillatory rotary motion is ca. 30°either side of a mean position, and the amplitude of the reciprocalmotion is ca. 1.0 mm. Numerous drive mechanisms are known in the art toachieve such motion.

Referring to FIG. 2 a bristle holder 20 is shown in a side view. FIG. 3shows a plan view looking down onto the surface 21, from which thebristle cluster 17 projects, along the rotation axis 22 about which theholder 20 rotates with oscillating rotation.

Mounted on the surface 21 are tufts of bristles 23, 24. These comprisefirst, outwardly leaning tufts 23 and second tufts 24 which are orientedparallel to the axis 22, i.e. perpendicular to surface 21. The tufts 23all lean outwardly along a radius from rotation axis 22, making an angleof ca. 10° with the orientation of the axis 22 so that their distal endsare radially further from the rotation axis 22 than their bases. Beingparallel to the axis 22, the distal ends of the second tufts 24 are atthe same radial distance from the axis 22 as their bases.

The bases of tufts 23, 24 are arranged in two respective regularpolygons each concentric around the rotation axis 22. The bases of allthe first tufts 23 are radially inward of the bases of all the secondtufts 24 so that the polygon of the bases of the first tufts 23 lieswithin and concentric with the polygon of bases of the second tufts 24.There are ten tufts 23 and ten tufts 24 in the respective polygons butthere may be more or less bases in each polygon.

It is also seen that outwardly leaning first tufts 23 are arrangedradially inward from gaps between adjacent second tufts 24 so that anoutwardly leaning tuft 23 leans outwardly between flanking pairs ofsecond tufts 24, and similarly a second tuft 24 extends parallel to theaxis 22 between flanking pairs of outwardly leaning first tufts 23.

FIG. 10 shows an arrangement similar to FIG. 2 and shows a view in thedirection of a tangent to a circle radially mid way between the polygonsof tufts 23 and 24. It is seen that the distal ends of tufts 24 areslightly further out radially than the distal ends of the tufts 23.

Referring to FIG. 4 a bristle holder 20 is shown in a side view lookingperpendicular to the rotation axis 22. FIG. 5 shows a plan view lookingdown onto the surface 21, from which the bristle cluster 17 projects,along the rotation axis 22.

Mounted on the surface 21 are tufts of bristles 23, 24. These comprisefirst, outwardly leaning tufts 23 and second tufts 24 which are orientedparallel to the axis D—D, i.e. perpendicular to surface 21. The tufts 23all lean outwardly along a radius from rotation axis 22, making an angleof ca. 10° with the orientation of the axis 22 so that their distal endsare radially further from the rotation axis 22 than their bases. Beingparallel to the axis 22, the distal ends of the second tufts 24 are atthe same radial distance from the axis 22 as their bases. The relativeleaning of the tufts 23, 24 is thus similar to FIGS. 2 and 3.

The cluster shown in FIGS. 4 and 5 comprises two polygons of first tufts231, 232, one 231 within the other 232, concentrically about therotation axis 22, having their first tufts 231, 232 leaning outwardly atthe same angle of ca. 8° relative to the rotation axis 22. The firsttufts 231, 232 are arranged on radii from the rotation axis 22. In thearrangement shown there are also two polygons of second tufts 241, 242,one 241 within the other 242, the second tufts 241, 242 being orientedparallel to the axis 22. The arrangement therefore comprises, proceedingradially outward from the rotation axis 22: a polygon of bases of firsttufts 231; a polygon of bases of second tufts 241 oriented parallel tothe rotation axis; another polygon of bases of first tufts 232; anotherpolygon of bases of second tufts 242 oriented parallel to the rotationaxis.

Each polygon of first tufts 231, 232 contains six tufts so the polygonis a hexagon. The inner polygon of second tufts 241 also contains sixtufts. The outer polygon of second tufts 242 contains twelve tufts so isa dodecagon. It is also seen that the outermost second tufts 242 arearranged in groups, i.e. pairs 242A, of circumferentially adjacentsecond tufts 242, so that first tufts 231 are circumferentially betweencircumferentially adjacent pairs of these groups of second tufts 242.

FIG. 11 shows an arrangement similar to FIGS. 4 and 5, showing a view inthe direction of a tangent to a circle radially mid way between thepolygons of tufts 241 and 242. It is seen that the distal ends of thetufts 231 are further out radially than the distal ends of the tufts.241, and that the distal ends of tufts 232 are slightly further outradially than the distal ends of the tufts 242.

Referring to FIG. 6 a bristle holder 20 is shown in a side view lookingperpendicular to the rotation axis 22. FIG. 7 shows a plan view lookingdown onto the surface 21, from which the bristle cluster 17 projects,along the rotation axis 22.

Mounted on the surface 21 are tufts of bristles 23, 241, 242. Thesecomprise first, outwardly leaning tufts 23 and second tufts 241,242which are oriented parallel to the axis D—D, i.e. perpendicular tosurface 21. The arrangement is similar to FIGS. 2 and 3 above. Firsttufts 23 are arranged in a regular pentagon, and second tufts 241,242are arranged in two polygons having respectively their bases furtherradially out 241, and at the same distance out 242 from the rotationaxis than the bases of the first tufts 23, and aligned parallel to therotation axis. In the outer polygon of second tufts 241 the tufts arearranged in circumferentially adjacent groups, i.e. pairs.

Referring to FIG. 8 a bristle holder 20 is shown in a side view lookingperpendicular to the rotation axis 22. FIG. 9 shows a plan view lookingdown onto the surface 21, from which the bristle cluster 17 projects,along the rotation axis 22.

Mounted on the surface 21 are tufts of bristles 23, 24. These comprisefirst, outwardly leaning tufts 23, which all lean outwardly along aradius from rotation axis 22, making an angle of ca. 12° with theorientation of the axis 22 so that their distal ends are radiallyfurther from the rotation axis 22 than their bases. The cluster alsocomprises second inwardly leaning tufts 24, which all lean inwardlyalong a radius toward rotation axis 22, making an angle of ca. 11° withthe orientation of the axis 22 so that their distal ends are radiallycloser to the rotation axis 22 than their bases.

The bases of tufts 23, 24 are arranged in two respective regularpolygons each concentric around the rotation axis 22. The bases of allthe first tufts 23 are radially inward of the bases of all the secondtufts 24 so that the polygon of the bases of the first tufts 23 lieswithin and concentric with the polygon of bases of the second tufts 24.There are nine tufts 23 and nine tufts 24, so the polygons are nonagons,but there may be more or less bases in each polygon.

It is also seen that outwardly leaning first tufts 23 are arrangedradially inward from gaps between adjacent second tufts 24 so that anoutwardly leaning tuft 23 leans outwardly between flanking pairs ofsecond tufts 24, and similarly a second tuft 24 extends parallel to theaxis 22 between flanking pairs of outwardly leaning first tufts 23.

FIG. 12 shows an arrangement similar to FIGS. 8 and 9, showing a view inthe direction of a tangent to a circle radially mid way between thepolygons of tufts 23 and 24. It is seen that the distal ends of tufts 23are further out radially than the distal ends of the tufts 24, and thatas seen superimposed upon each other the tufts 23, 24 are seen to cross.

FIGS. 2-9 also show the presence of other, third, tufts of bristles 25.Although these are shown oriented parallel to the axis 22 they mayalternatively lean inwardly toward or outwardly from the rotation axis22. Such bristles 25 may be arranged at other points on the surface 21to that shown, for example to increase the packing density of thebristle cluster. In the arrangements shown these third tufts 25 form aninnermost polygon of tufts arranged around the axis of rotation 22, andextend further from the surface 21 than do the first and second tufts23, 24, which all have their distal ends at the same perpendiculardistance from surface 25.

All or some of the tufts of bristles 23, 24, 25 may also include acomponent of lean (not shown) in and/or against the direction ofrotation of the holder 20 about axis 22.

FIG. 13 shows another arrangement of first 23 and second 24 tufts, inwhich first tufts 23 project from surface 21 of the bristle holder 20,having their bases arranged in a polygon (not shown) around the rotationaxis, leaning outwardly away from the rotation axis so that their distalend is further out from the rotation axis than their base. In thearrangement second tufts 24 also lean outwardly away from the rotationaxis so that their distal end is further out from the rotation axis thantheir base, and their base is further radially out from the rotationaxis than the bases of the first tufts 23, but the tufts 24 have alesser angle of lean relative to the rotation axis than the first tufts23. The view of FIG. 13 is at a tangent to a circle radially mid-waybetween the bases of the tufts 23, 24 and as seen superimposed upon eachother the tufts 23, 24 are seen to cross.

Referring to FIG. 14, a plurality of first tufts 23 project from thesurface 21 of the bristle holder 20, and have their bases arranged in apolygon around the rotation axis 22 as in the embodiments illustratedabove. The first tufts 23 lean outwardly away from the rotation axis 22so that their distal end is further out from the rotation axis 22 thantheir base.

There is also a plurality of second tufts 24 which also have their basesarranged in a polygon around the rotation axis 22 as in the embodimentsillustrated above. In FIG. 14 the second tufts 24 are oriented parallelto the rotation axis 22, but they could lean as in the other illustratedembodiments.

The first 23 and second 24 tufts have their bases at different radialdistances R¹, R² from the rotation axis D—D, R¹ being less than R², witha difference R² minus R¹ being d¹. The first 23 and second 24 tufts areoriented relative to the rotation axis 22 such that at a point, e.g. P¹,P² along their base-distal end length the first 23 and second 24 tuftsare respectively at radial distances from the rotation axis 22 with adifference d² in their respective radial distances less than thedifference d¹ in the radial distances R¹, R² of their bases from therotation axis 22. It is seen that the difference d² is minimal at thedistal ends on the tufts 23, 24. The same principle is seen to apply tothe embodiments illustrated in FIGS. 10-13, and in FIGS. 11, 12 and 13it is seen that d² drops to zero at a point as the tufts 23, 24 are atthe same radial distances from the rotation axis 22, but proceedingfurther in the base-distal direction d² again increases as the tufts23,24 diverge in their radial distance.

FIGS. 15-20 illustrate a brush part according to the second aspect ofthis invention.

Referring to FIG. 15, FIGS. 15A and 15B show perspective views of abristle holder 20, on a surface 21 of which a bristle cluster 17 ismounted. FIG. 15C shows a plan view of the cluster 17 and holder 20,looking down on surface 21 along the axis 22 about which holder 20rotates with oscillating rotation.

As seen in FIGS. 15A, 15B and 15C, the cluster 17 comprises a pluralityof tufts of bristles arranged in two regular polygons of tufts, viz. afirst, inner polygon 23 of twelve tufts and a second outer polygon 24 ofeighteen tufts surrounding the inner polygon 23. Both the inner 23 andouter 24 polygons are arranged around a common centre. In both polygons23, 24 all of the tufts are mounted inclined at an angle such that thedistal end 23A,24A of the tuft (furthest from the surface 21 of thebristle holder 20) is further around the polygon which contains it thanthe opposite base end 23B,24B of the tuft mounted in the surface 21, bythe distance “d” shown in FIG. 15C. In these inner 23 and outer 24polygons their respective inclined tufts are inclined in oppositedirections around the polygons 23, 24, such that the tufts in the innerpolygon 23 are inclined in a clockwise direction, whilst the tuft(s) inthe outer polygon 24 are inclined in an anti-clockwise direction. Thetufts in both polygons 23,24 are inclined at ca. 75° to the flat surface21 of the bristle holder 20.

The tufts 23,24 are also aligned outwardly angled relative to the centreof the polygon as viewed in plan, relative to the direction of anadjacent side of the polygon, by the angle A seen in FIG. 15C.

The cluster 17 also includes a polygon 25 of six third bristles having acommon centre with the polygons 23, 24, situated within and surroundedby the inner polygon 23. The tufts of this third polygon 25 aresubstantially parallel to the axis of rotation 22 of the holder 20. Atthe centre of all three of the polygons 23, 24, 25 is a single thirdtuft 26, also aligned substantially parallel to the axis of rotation 22.

As viewed in plan, the clusters 17 of FIGS. 15, 16, 17 and 18 areidentical, but these clusters differ in the profile of the ends of thetufts remote from the surface 21 of the bristle holder 20.

In FIGS. 15, 16 and 17 the ends of the two outer polygons 23, 24 are cutso as to lie in a plane parallel to the bristle surface 21.

In FIG. 15 the ends of the tufts of the innermost polygon 25 and thecentral tuft 26 are profiled to form a peak about the centre of thecluster 17. The ends of the tufts of the innermost polygon 25 are cut soas to incline upwards toward the centre 22 of the polygon in a generallyconical shape with its apex pointing away from the bristle surface 21.

FIG. 16 shows a similar arrangement, but with the ends of the tufts ofthe innermost polygon 25 profiled into a generally hemispherical domeshape.

In FIG. 17 the ends of the tufts of the tufts of the innermost polygon25 are profiled to incline downwards toward the centre 22 of thepolygons 23,24,25 in a generally conical shape with its apex pointingtoward the bristle surface 21.

In FIG. 18 the ends of all of the tufts 23,24,25,26 are profiled in aconcave cylindrical surface having the longitudinal axis of the cylinderC—C aligned perpendicular to the axis of rotation 22.

Referring to FIG. 19, FIG. 19A shows a plan of the arrangement of tuftsof bristles, and FIG. 19B shows a section through the cluster parallelto the axis of rotation. As seen in FIG. 19A the cluster 17 comprises aplurality of tufts of bristles arranged in two regular polygons, viz. afirst, inner polygon 23 of eight tufts and a second outer polygon 24 oftwelve tufts surrounding the inner polygon 23. Both the polygons 23,24are arranged around a common centre being rotation axis 22. In bothpolygons 23, 24 all of the tufts are mounted inclined at an angle suchthat the distal end of the tufts are further around the polygon whichcontains them than the base end, the inclination of only one tuft 231,241 in each of the polygons 23, 24 being shown in FIG. 19A which is aprojection on a plane perpendicular to the axis of rotation 22. In theseinner 23 and outer 24 polygons their respective inclined tufts areinclined in opposite directions around the polygons 23, 24, such thatthe tufts in the inner polygon 23 are inclined in a clockwise direction,whilst the tufts in the outer polygon 24 are inclined in an anticlockwise direction. The tufts in polygons 23,24 are also alignedoutwardly angled relative to the centre 22 of the polygon, relative tothe direction of an adjacent side of the polygon.

The cluster 17 also includes an innermost polygon 25 of four thirdbristles in a regular square having a common centre with the polygons23, 24, the tufts of third polygon 25 being substantially parallel tothe axis of rotation 22 of the holder 20.

As seen in the sectional view of FIG. 19B, being a sectional viewthrough the bristle cluster 17 cut through rotation axis 22, the ends ofthe tufts 23,24,25 are profiled to form a peak about the centre of thecluster, the tufts of the innermost polygon 25 being the highest, thetufts of intermediate polygon 23 being lower than both the tufts of theoutermost 24 and innermost 25 polygons, so that the height of thepolygons dips between the outermost 24 and innermost 25 polygons.

Referring to FIG. 20, FIG. 20A shows a plan of the arrangement of tuftsof bristles at the bristle surface 21. FIG. 20B shows a plan view of thecluster looking down the rotation axis 22 onto the surface 21. FIG. 20Cshows a side view perpendicular to the axis of rotation 22. As seen inFIGS. 20A and 20B the cluster 17 comprises a plurality of tufts ofbristles arranged in two regular polygons, a first inner regular polygon23 of eight tufts and a second outer regular polygon 24 of twelve tuftssurrounding the inner, polygon 23, both polygons 23,24 being arrangedaround a common centre.

As seen in FIG. 20B in both polygons 23, 24 all of the tufts are mountedinclined at an angle such that the distal end 23A, 24A of the tuft isfurther around the polygon which contains it than the opposite base end23B,24B of the tuft, the respective inclined tufts being inclined inopposite directions around the respective polygons 23, 24. In twoversions of the FIG. 20 embodiment the inclination of the tufts of theouter polygon is 8° or 10°, and the respective inclination of the tuftsof the inner polygon is 4° or 5° in the opposite direction. The tufts ofthe outer polygon 24 are also aligned outwardly at an angle 5° relativeto the centre of the polygon as viewed in plan, relative to thedirection of an adjacent side of the polygon, whilst the tufts 20 of theinner polygon 24 are aligned parallel to the direction of an adjacentside of the polygon.

The cluster 17 also includes an innermost polygon 25 of four thirdbristles in a regular square having a common centre with the polygons23, 24, the tufts of which are substantially parallel to the axis ofrotation 22 of the holder 20, and the distal ends of the which arehigher than the tufts 23,24, the ends of which lie in a plane. Theheight of the tufts 24 above surface 21 is 8 mm and of the tufts 23,24is 6 mm.

1-12. (canceled)
 13. A brush part for an electric toothbrush whichincludes a bristle holder mounted for rotary motion about a rotationaxis, a plurality of first tufts projecting from a surface of thebristle holder and having their bases arranged in a polygon around therotation axis and leaning outwardly away from the rotation axis so thattheir distal end is further out from the rotation axis than their base,and a plurality of second tufts projecting from a surface of the bristleholder and having their bases arranged in a polygon around the rotationaxis, characterized by: the first and second tufts having their bases atdifferent radial distances from the rotation axis, the first and secondtufts oriented relative to the rotation axis such that at a point alongtheir base-distal end length the first and second tufts are respectivelyat radial distances from the rotation axis with a difference in theirrespective radial distances less than the difference in the respectiveradial distances of their bases from the rotation axis.
 14. A brush partaccording to claim 1 wherein the bases of the second tufts being locatedat a greater radial distance from the rotation axis than are the basesof the first tufts.
 15. A brush part according to claim 13 wherein at apoint along their base-distal end length, the first and second tufts arerespectively at the same radial distances from the rotation axis so thatthe difference in their respective radial distances is zero.
 16. A brushpart according to claim 15 wherein at a greater distal distance alongtheir base-distal end length the difference in the respective radialdistances from the center increases.
 17. A brush part according to claim13 wherein by first and second tufts circumferentially adjacent to eachother at the point of minimum difference in their respective radialdistances, on a circle centered on the rotation axis.
 18. A brush partaccording to claim 13 wherein a plurality of second tufts having theirbases further radially out from the rotation axis than the bases of thefirst tufts, and aligned parallel to the rotation axis.
 19. A brush partaccording to claim 13 wherein a plurality of second tufts having theirbases further radially out from the rotation axis than the bases of thefirst tufts, and leaning inwardly toward the rotation axis so that theirdistal ends are at less distance radially from the rotation axis thantheir base.
 20. A brush part according to claim 13 wherein a pluralityof second tufts having their bases further radially out from therotation axis than the bases of the first tufts, and leaning outwardlyaway from the rotation axis so that their distal end is further out fromthe rotation axis than their base, but at a lesser angle of leanrelative to the rotation axis than the first tufts.
 21. A brush partaccording to claim 13 wherein the distal ends of the first tufts arefurther radially out than the distal ends of the first tufts.
 22. Abrush part according to claim 21 wherein the respective lean of theoutwardly leaning first tufts and the orientation of the second tufts issuch that as viewed along a line tangential to a circle centered on therotation axis and mid way between the bases of the first and secondtufts circumferentially adjacent first and second tufts as seensuperimposed are seen to cross each other.
 23. A brush part according toclaim 13 wherein a polygon of bases of the second tufts which liesoutside and is concentric with the polygon of bases of the first tufts.24. An electric toothbrush provided with a brush part according to claim13.